retrieve multiple objects from one which is array of objects in mongodb

Question

I using mongodb to save my user data along with array. My question is how to retrieve multiple objects that matches the given value in that user array.like this:

{ 
    _id: { objid:'0000000000000' },
    userId: 'abc',
    userItems : [
        {
            itemName: 'mango',
            date: 24,
            month: 1,
            year: 2016
        },
        {
            itemName: 'apple',
            date: 24,
            month: 1,
            year: 2016
        },
        {
            itemName: 'orange',
            date: 22,
            month: 1,
            year: 2016
        },
        {
            itemName: 'vanilla',
            date: 23,
            month: 1,
            year: 2016
        }
    ]
}

and expeccted result is

{
    _id: { objid: '0000000000000' },
    userId: 'abc',
    userItems: [
        {
            itemName: 'mango',
            date: 24,
            month: 1,
            year: 2016
        },
        {
            itemName: 'apple',
            date: 24,
            month: 1,
            year: 2016
        }
    ]
}

I want all the element that matches the date,month,year from this userId userItems array please help me out from this

Possible duplicate of Retrieve only the queried element in an object array in MongoDB collection — Sede
– Sede, Commented Jan 29, 2016 at 19:09

Somnath Muluk · Accepted Answer · 2016-01-29 19:23:11Z

1

We can find result by aggregation framework.

db.user.aggregate(
   {
     $unwind : "$userItems" 
   },
   {
      $match: {
        "userItems.date" : 24, 
        "userItems.month" : 1, 
        "userItems.year" : 2016
      }
   },
   {
      $group: {
         "_id" : { "id":"$_id","userId":"$userId"},
         "userItems" : {$push:"$userItems"}
      }
   },
   {
       $project:{
          "_id": "$_id.id", 
          "userId": "$_id.userId",
          "userItems": 1 
       }
   }
)

answered Jan 29, 2016 at 19:23

Somnath Muluk

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4 Comments

VSO Over a year ago

I have seen that format before, but I have never used it, so I can't comment on whether or not the best way. Upvoting anyway, because I know it's one of the ways to do it.

Somnath Muluk Over a year ago

This is the best thing in mongo, you must learn. Aggregation framework is good for Grouping and projecting required data. Best when collection size is getting bigger and bigger.

Muhammad Sami Over a year ago

Thank you all this answer solved my problem but for my issue i dont need $projection. Thanks Thankyou all

Somnath Muluk Over a year ago

Welcome. I have given $projection to give knowledge about how you can project result coming from group. This project will give object similar to your input. You can use projection or not, that's your need. If someone pointing to you to right direction or answer, you should accept answer. You must not have visited the link I have given in last comment. People see your acceptance ratio.

VSO · Accepted Answer · 2016-01-29 19:04:50Z

0

db.collectioName.find(
   {
      nameOfArrayYouarelookingIn: {
         $elemMatch: {
            ArrayFieldOneName: 1,
            ArrayFieldTwoName: 'blahblah'
         }
      }
   }
)

See $elemMatch documentation for more details and examples.

answered Jan 29, 2016 at 19:04

VSO

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2 Comments

Muhammad Sami Over a year ago

I have used it but it only gives me the first matching object not more than that

Somnath Muluk Over a year ago

this will match whole document. and not give matching objects inside of array property. @VSO check my answer

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